1. Field of the Invention
The present invention relates to a mobile telephone apparatus used in a car, and more specifically, the present invention relates to a mobile radio telephone apparatus to which a power supply from a car battery may be turned off by either one of a power switch or an ignition switch.
2. Description of the Relevant Art
A mobile radio telephone apparatus is supplied power from a car battery mounted on a car. A position of an ignition switch of the car affects the operability of the mobile radio telephone.
The ignition switch may be switched into four different positions. The four positions are an OFF position, an accessory (ACC) position, an ON position, and a START position. When the ignition switch is in the ACC position or the ON position, the radio telephone apparatus can be turned on by operating a power switch of the apparatus. When the ignition switch is in the OFF position or the START position, the radio telephone apparatus cannot be turned on.
A user of the radio telephone apparatus may turn on the radio telephone apparatus by first switching the ignition switch into the ACC position or the ON position and operating the power switch of the apparatus itself. After that, if the user switches the ignition switch into the OFF position or the START position, the mobile radio telephone apparatus is turned off accordingly. In the event that the ignition switch is switched to the OFF position, according to the conventional radio telephone apparatus, the operational state set by the power switch is lost. This is because the power switch of such a radio telephone apparatus is constituted by an electronic switch which is different from a mechanical switch. Consequently, when the user wishes to turn on the radio telephone apparatus again, the user has to operate both of the ignition switch and the power switch.
Still, the loss of the operational state of the radio telephone apparatus will occur every time the user switches the ignition switch into the START position in order to start the engine of the car. Therefore disadvantageously, the user always has to turn on the radio telephone apparatus again after the user starts the engine.